On CUDA, check that a team policy won't throw due to team_size too large exception

Kokkos asks Cuda to compute the max number of blocks, which is then used to compute the max team_size. If the requested team_size is too large, it throws.

Currently, our simulations never crashed, as long as build type of kokkos and homme match (debug-debug or release-release). However, we should not rely on this being always the case. Hence, upon policy creation, check if policy numbers are ok; if not, keep reducing either vector_length or team_size (depending if threads are preferred) until they are.

Start by locating policy creation and the CUDA path that computes the maximum blocks and team_size. Reproduce a request with an oversized team_size under differing build types, then verify that policy creation reduces vector_length or team_size according to the thread preference instead of throwing.

Written by the indexing model from the issue text.